User interface for a portion of a display screen



The FIGURE is a front view of a user interface for a portion of a display screen showing my new design.

The pair of horizontal evenly spaced dashed lines represents an actual depiction of a portion of the claimed design. The uneven broken line showing of the window and the display screen is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 